Semiconductor processing is generally performed in a highly controlled manner, with strict controls on environments and tool operations. Clean rooms that house these tools, for instance, must meet strict requirements that limit the amount of particles that can be generated during operation, and other controlled parameters. Substrates, when in process, may be required to move between many systems, and many times, the movements between the systems are repeated many times depending on the desired devices, layers and structures that need to be processed to create an integrated circuit device.
Although semiconductor equipment must meet tight regulations to qualify for production of semiconductor wafers, these regulations are most usually coupled to the individual tools. In operation, if a wafer needs to be processed in a wet tool, the tool completes its processing and then the substrate will have to be transported to another tool, which may be dry. In production, these substrates may be moved between tools using clean room automated systems. Typically, substrates are transported or moved in closed containers, and then coupled to other tools. Thus, if a plasma processing operation is needed, the substrate(s) may be moved to a cluster tool, which is defined by one or more transfer modules and dry processing modules.
Plasma processing modules are generally tied together in a cluster, but the cluster is limited to types of plasma processing or processes having a same ambient. That is, if the processing is dry (e.g., plasma processing), the substrate will be handled within that cluster until the process requires movement to a different type of system. Transport of the substrates between modules and clusters is handled in a very careful way, however, substrates are exposed to oxygen. The oxygen may be the oxygen present in the clean room (or closed containers), and although the environment is controlled and clean, exposure to oxygen during a movement can cause oxidation of features or layers, before a next operation can be performed. Many times, the simple known exposure to oxygen during transport within the clean room causes fabrication sequences to include additional oxide removal steps, at more cost and cycles. However, even if oxide removal steps are performed, the queue time before a next step may still cause the generation of some oxidation.
In view of the foregoing, there is a need for systems, structures and methods for handling substrates during the fabrication process, while avoiding unnecessary exposure to an uncontrolled ambient.